A salt-inducible chloroplastic monodehydroascorbate reductase from halophyte Avicennia marina confers salt stress tolerance on transgenic plants
A salt-inducible chloroplastic monodehydroascorbate reductase from halophyte Avicennia marina confers salt stress tolerance on transgenic plants
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DOI：
10.1016/j.biochi.2010.06.009
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发表时间：
2010-10-01
期刊：
影响因子：
3.9
通讯作者：
Parida, Ajay
中科院分区：
文献类型：
--
作者：
Kavitha, Kumaresan;George, Suja;Parida, Ajay
植物的生长和生产力受到各种非生物胁迫因素的不利影响。在我们之前的研究中，我们使用盐生红树林白骨壤作为分离耐盐基因的模式植物系统。从一个月大的滨海相思植物叶片组织文库中进行大规模随机EST测序，发现了一个与单脱氢抗坏血酸还原酶(AM-MDAR)同源性最高的克隆。MDAR在从一脱氢抗坏血酸中再生抗坏血酸以清除ROS中起着关键作用。在本文中，我们报道了这种盐诱导AM-MDAR基因在转基因烟草中的细胞定位和耐盐性。在Am-MDAR的N-末端有一个转运肽，提示它编码一个氯化异构体。Am-MDAR-GFP融合蛋白在烟草中的稳定转化和表达证实了叶绿体的定位。与对照相比，高表达Am-MDAR的转基因烟草在盐胁迫条件下存活得更好。对抗坏血酸谷胱甘肽循环相关酶的分析表明，在盐胁迫和非胁迫条件下，转基因植株的MDAR和抗坏血酸过氧化物酶活性增强，而脱氢抗坏血酸还原酶活性降低。转基因植株的抗坏血酸氧化还原状态增强，丙二醛水平降低，表明其对氧化胁迫的耐受性增强。我们的研究结果可以作为重要经济植物耐盐基因工程的起点。(C)2010年爱思唯尔·马森公司。版权所有。
Plant growth and productivity are adversely affected by various abiotic stress factors. In our previous study, we used Avicennia marina, a halophytic mangrove, as a model plant system for isolating genes functioning in salt stress tolerance. A large scale random EST sequencing from a salt stressed leaf tissue cDNA library of one month old A. marina plants resulted in identification of a clone showing maximum homology to Monodehydroascorbate reductase (Am-MDAR). MDAR plays a key role in regeneration of ascorbate from monodehydroascorbate for ROS scavenging. In this paper, we report the cellular localization and the ability to confer salt stress tolerance in transgenic tobacco of this salt inducible Am-MDAR. A transit peptide at the N-terminal region of Am-MDAR suggested that it encodes a chloroplastic isoform. The chloroplastic localization was confirmed by stable transformation and expression of the Am-MDAR-GFP fusion protein in tobacco. Transgenic tobacco plants overexpressing Am-MDAR survived better under conditions of salt stress compared to untransformed control plants. Assays of enzymes involved in ascorbate glutathione cycle revealed an enhanced activity of MDAR and ascorbate peroxidase whereas the activity of dehyroascorbate reductase was reduced under salt stressed and unstressed conditions in Am-MDAR transgenic lines. The transgenic lines showed an enhanced redox state of ascorbate and reduced levels of malondialdehyde indicating its enhanced tolerance to oxidative stress. The results of our studies could be used as a starting point for genetic engineering of economically important plants tolerant to salt stress. (C) 2010 Elsevier Masson SAS. All rights reserved.